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    Results 1 to 13 of 13
    1. #1
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States

      Brake pedal not returning all the way

      I'm having an issue where my brake pedal returns maybe 90-95% but then stops, brake lights are still on and if I'm cruising through a parking lot I can smell the brakes, the car also wants to stop unless on I'm on the gas, not a violent stop but enough that I don't have to hit the brakes pulling into a parking spot. I can put my foot under the brake pedal and lift it but it almost feels like it's slightly stuck, it's not hard to pull back but again just feels a little hung up. I've looked under the dash with a flashlight and can't see anything that it'd be hung up on but it all seems clear.

      I'm thinking of just buying brake pedal return spring but I feel like maybe that's not fixing the cause, or maybe it is and I should have installed a spring in the first place?

      I have wilwood aero 6 brakes in front and aero 4 in the rear, right stuff 9" booster, and wilwood master cylinder/proportioning valve.



    2. #2
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      3,851
      Country Flag: United States
      Does your engine produce low vacuum? I went through this with a cam that produced low vacuum.

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain

    3. #3
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States
      I haven't hooked up a gauge to see what the vaccum is at but I did notice the power brakes weren't working as well after a cam swap, I added a vaccum canister to be safe and brakes are working better than they were.

      This issue goes back to before the cam swap, i notice it more after the cam swap but that could be that I also noticed the pedal post cam swap and not just the slowing down in parking lots. I don't know if I'm noticing it now more because I know about the issue or maybe you're on to something with the low vaccum.

      What should my vaccum be at? I can snag a cheap gauge to check it out.

    4. #4
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      3,851
      Country Flag: United States
      Hard to give an exact number for minimum. A lot of cars now have vacuum pumps. Normal vacuum is around 18 afaik.

      Hopefully someone smarter will chime in.

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain

    5. #5
      Join Date
      Sep 2004
      Location
      Arizona
      Posts
      225
      There is a spring inside the booster which should be adequate to return the pedal to the up position without an additional return spring. I had a Right Stuff booster that did the same thing. They replaced it. Problem drove me nuts, turns out I had a bad master AND a bad booster....After long discussions about they have never had a booster fail like that...Yada yada yada .... it was the booster and a leaky master.... replaced them both and all works as it should.

    6. #6
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States
      Sounds like I need to pull the booster off the firewall and test that spring. Too bad I bought all this stuff years ago and had it sitting in boxes waiting for mockup, only having 400ish miles on the car and having parts failures isn't fun. Thanks for the info guys!

    7. #7
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      3,851
      Country Flag: United States
      Quote Originally Posted by k72nova View Post
      Sounds like I need to pull the booster off the firewall and test that spring. Too bad I bought all this stuff years ago and had it sitting in boxes waiting for mockup, only having 400ish miles on the car and having parts failures isn't fun. Thanks for the info guys!
      Would be a whole lot easier to measure your vacuum first. Just sayin…

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain

    8. #8
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States
      Quote Originally Posted by dhutton View Post
      Would be a whole lot easier to measure your vacuum first. Just sayin…

      Don
      You're right, I'm going to stop by auto zone today for a vacuum gauge just to verify and cause I like buying tools! It seems like it has to be more than that but I've been wrong more than I've been right with this car.

      I found another post with something similar and the issue was the booster boot that goes through the firewall. That goes back to removing the booster but again I'll test the vacuum first.


      Link to the thread I mentioned if anyone's curious...

      https://www.pro-touring.com/threads/...pedal-sticking

    9. #9
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States
      Ok I got a vacuum gauge and I'm at 10 in hg at idle and 15 when sitting at 2k rpm. Seems a bit low but 15 is in the green on the gauge, not sure if that really means much. So even though that's a bit low at idle ( think) I tested the brakes while keeping the roms up going down the street and the pedal still sticks. I'm starting to lean more towards the booster. I'll have to do a bit of digging to find more though because if 15 is still too low then maybe I do need a vacuum pump. I don't feel like I have a leak since I heard a hiss of air when I pulled the hose off to hook up the gauge after the car had been sitting idle for a few minutes.

    10. #10
      Join Date
      Aug 2007
      Location
      Jonesboro, Arkansas
      Posts
      2,483
      Country Flag: United States
      I had a very similar problem, mine was that the rod going from the booster to the brake pedal was a fraction too long. What would happen was, as the brake system heated up the fluid did to. All that increase has to go somewhere and it pushed fluid against the rod. I could pull over and loosen the booster about a quarter inch and make it home. I got a different rid that was shorter and problem solved! I did have to put a helper spring on the brake pedal to bring it up against the stop under the dash but that was so the clutch pedal and brake pedal would be even.

      Carl Wilson
      1968 Camaro - T-56 6 speed - 383 Stroker, 2014 Mustang GT seats

    11. #11
      Join Date
      Dec 2002
      Location
      MusicCity
      Posts
      473

      Another BIG problem to factor in

      Another BIG problem to factor in is that carbureted engines will leach fuel vapors into the vacuum booster as the check valve can't hold 100% at all times. So picture a vacuum built up in the booster, you just shut the engine off, and now fuel vapors from the intake are slowly getting sucked into the vacuum brake booster. Today's ethanol fuels are worse than ever for this. The OEM late model carbureted cars had a small inline vapor canister between the intake and the vacuum booster to help prevent this from happening. It worked, but not 100%, especially if hit with today's gasoline. Once the fuel vapors are inside of the vacuum booster, it can swell up the rubber diaphragm(s) and seals causing your condition. What to do? The only way to prevent this from happening is to get in the habit of killing the engine, then applying the brakes a few times to blow off any stored vacuum in the booster. A couple of full applies is plenty. When you fire the engine back up, you will feel the brake pedal sink down as the booster is energized back up with fresh vacuum.

      NOTE: The above does not apply to a fuel injected vehicle because the injectors are shut off while the engine is still spinning, drawing out any and all fuel vapors out of the intake while it winds down to a complete stop.

      In some VERY rare cases, just getting in the habit of depleting any stored vacuum in the brake booster when parking can eventually dry out any swollen diaphragms and seals, allowing the vacuum booster to start behaving normally again - rare, but worth a shot before pronouncing the vacuum booster dead.

      Things that make you go hmmmm....

      There IS a difference - Thank you for choosing Hydratech!

      Paul M. Clark
      Founder / Master Engineer

      Hydratech Braking Systems ®
      www.hydratechbraking.com

    12. #12
      Join Date
      Feb 2012
      Posts
      56
      Country Flag: United States
      Interesting stuff about fuel vapors, I had no idea. This one's fuel injected so I should be safe there but I appreciate that info!

    13. #13
      Join Date
      Dec 2002
      Location
      MusicCity
      Posts
      473

      Pedal rod angularity

      One more further thing to check is to temporarily disconnect the brake pedal rod from the brake pedal. If it naturally wants to sit an inch +/- higher or lower than your current pedal rod connection point while disconnected, something is causing the brake booster not to target the mounting angle correctly (such as an aftermarket mounting bracket kit that is off). Also check and make sure the pedal swings freely through its full range of motion with the brake pedal rod disconnected, as the swing pivot bushings at the top of the pedal could be seizing up. Vacuum brake boosters have a very low tolerance for the brake pedal rod being off of dead straight, as this wreaks havoc with the bushings and valving inside of the booster. If you find this to be the case, investigate the brake booster mounting as the primary usual culprit - sometimes you have to swap out the vacuum booster mounting brackets to a different brand / type / style, or modify the mounting angle via some slight shim work (a washer or two in a target location to bring the booster angle up or down. The other way to deal with this would be to move the connection point on the brake pedal to accommodate where the booster rod wants to naturally sit as needed. If this is a '72 Nova (?), then it is a horseshoe clevis type connection, which means you would only have to drill an alternate 3/8" clevis cross pin hole into the pedal. Last but not least, some have had strange problems with the brake boosters that have a later model accordion belows type of rear firewall dust seal, versus the factory injection molded plastic firewall tube seal. I know that DSE had a problem with that, where some customers had to remove their brake booster and oblong the firewall pass through hole upwards to clear up a binding issue. I have never personally seen any vacuum issue (high or low) not allow a brake pedal to return to its full resting position unless the booster was internally damaged.

      Hope this helps!
      There IS a difference - Thank you for choosing Hydratech!

      Paul M. Clark
      Founder / Master Engineer

      Hydratech Braking Systems ®
      www.hydratechbraking.com